Regulators are an essential component of most electronic devices which operate at a specified DC voltage or current. Typically, the electronic devices are powered with a source voltage that is fluctuating (e.g., provided by a power supply connected into a wall socket) or at an inappropriate amplitude (e.g., provided by a battery). The purpose of a regulator is to convert the source voltage into the operating DC voltage or current of the electronic devices.
One type of a commonly used regulator is a switching regulator. Switching regulators employ one or more switching elements and an inductor, transformer, and/or a capacitor as an energy storage element between the source and the load. The switching elements may be, for example, power metal-oxide semiconductor field-effect transistor (MOSFET) switches. The switching regulator regulates the voltage or current across the load by varying the ON-OFF times of the switching elements so that power is transmitted through the switching elements and into the energy storage element. The current pulses may be generated by one-shot timers or other circuitry. The energy storage element converts the current pulses into a steady load current so that the load voltage is regulated.
Switching regulators may be designed in a single monolithic device that integrates all of the switching elements inside the device. Monolithic switching regulators reduce the design complexity, improve reliability, and are easier to maintain than traditional regulators. Additionally, they may be designed with multiple channels in a multi-channel configuration.
Multi-channel monolithic switching regulators provide more than one channel in a single device. A channel consists of a switching element and associated energy elements. They may be more efficient in terms of device utilization than single-channel switching regulators and reduce the number of external components required for power management in an electronic device. An example of a multi-channel switching regulator includes the LTC3407 sold by Linear Technology Corporation, of Milpitas, Calif.
Both single-channel and multi-channel switching regulators lack the flexibility of current programming. The maximum current of a monolithic switching regulator is usually fixed by design and cannot be scaled up or down by the designer. The designer cannot typically select the portion of total current that is allocated to each channel.
For example, a designer of a dual-channel 2 A/2 A power supply that delivers 2 A on each channel needs to use a different dual-channel monolithic switching regulator than a designer of a dual-channel 3 A/1 A power supply that delivers 3 A on one channel and 1 A on the other channel, even though the total current output of the two power supplies is the same. Such inflexibility adds development and bill-of-material costs to power supply designers. A 3 A/1 A power supply designer often ends up using a 3 A/3 A monolithic switching regulator because of the limited design selection offered by IC manufacturers.
In view of the foregoing, it would be desirable to provide circuits and methods for providing flexible current partitioning among the multiple channels in a multi-channel monolithic switching regulator.
It further would be desirable to provide circuits and methods for autosensing the channel connections for programming current partitioning in multi-channel monolithic switching regulators.
It also would be desirable to provide circuits and methods for converting a multi-channel, multi-output switching regulator into a multi-channel, single-output regulator and into a single-channel, single-output regulator using current partitioning.